Sol-Gel-Derived Iron Oxide Thin Films on Silicon: Surface Properties and Interfacial Chemistry

Uniform high-quality iron oxide thin films can be formed from the spin coating of iron oxide/hydroxide sol-gels on a silicon substrate. Thermal processing of the films at temperatures of similar to 300 degrees C results in the transformation of films into a ternary layered structure with Iron oxide, Fe2O3, at the surface, characterized by Mossbauer spectroscopy. and reduced Metallic iron characterized by depth profiling of the surface by X-ray photoelectron spectroscopy as a function of Ar+ etching. Imaging of the etched surface by scanning electron microscopy reveals two distinct regions at the interface, nanoparticles that are very iron-rich separated by an unstructured region that is somewhat less iron-rich. The results demonstrate a synthetic protocol for the spontaneous formaton of a ternary layered structure from a simple one-step preparation.